Rectifier for alternating electric current



Jan- 1, 1935 R, J. ELsoME-JONES RECTIFIER FOR ALTERNATNG ELECTRIC CURRENT Filed Aug. 12, 1951 erties i. e., unidirectional conducting properties v Patented Jan. l, 1935 l v.AiLTrzaNAfrmd ELECTRIC CURRENT anonima Fon PATENT* OFFICE Ronald Jobl Elsome-Jones, Gelders Green, London, England, assignor to International Standard Electric Corporation, New York,'N. Y., a corporation of Delaware Application August 12, 1931, Serial- No. 556,658 In Great Britain August 12, 1930 's clam (01. 175-366) This invention relates to static contact dry rectiiiersfor alternating electric currents using solid couples with asymmetric conducting propor conducting properties more pronounced in one direction than in another.

The chief features of the invention consist in the incorporation of a barium compound on one electrode of each' couple; in the provision of a rectifier in which both electrodes of each couple make oxide-to-oxide contact; and in the 'provision of an electrode alloy of aluminium, manganese, and magnesium that incorporates a barium'compound.

In carrying out the invention I alloy the alu. minium manganese and magnesium preferably inthe percentages of 12, 1/2, and 871/2 respectively, and turn, stamp, or otherwise form the said all loy into discs or other bodies of suitable shape.

The proportions of the above elements may vary between V2% to 20% aluminium and 20% to 5% manganese, or in any other proportions provided the resulting alloy is satisfactorily workable.

The discs or the like are immersed in an electrolytic bath consisting of a barium salt in solution so as each to have a nlm of barium deposited on one face. The bath may .consist of a 10% solution of chemically pure barium sulphide,.

. slightly acidified, and the electrolyzing direct Y `lead alloy, or other suitable metal. Variations from the proportions of the materials in the paste will give a workable electrode and I may include in the said paste small quantities of cuprous. lead,

or' mercurous iodide, zinc sulphide, and lead sulphide. y

v The paste is made by grinding and mixing the constituents and then mixing the resulting ,powder with a. selenious-phosphoric acid solution .w acid and 6% solution phosphoric acidf with the weights of. thefour'main constituents in 4drams.

of say 6% strength, i. e. 6% solution selenious the solution is preferably c. c. by volume. The solution containing thepcwder is boiled'to dryness, reg-round, and compressed into a solid o layer directly on to the barium-coated surface,"

preferably after a small quantity of a metallic sulphide such as ferric sulphide or other suitable compound or element has been added to the reground mixture-in order to prevent the compressed layer becoming undesirably brittle. The

compressed layer should not exceed of an inch in thickness for best results.

A rectifier or rectiers consisting of one or more couples as above set out may be suitably assembled and inserted in an alternating current circuit'wth the outer faces of the couplesjoined by the brass or like plates above mentioned.

The couples may be, however, worked vin circuit fora shortperiod and the electrodes separated and then replaced in close contact but not neces# sarily under high pressure, and when the couples are connected in circuit vagain the complex oxides apparently formed on each electrode due to the passage of the initial current assist or perform rectification. Such an arrangement differs from previous proposals in that due to the low resist- 'ances of the electrodes, and oxides according to the invention, high pressure contact is not neces-l sary and rectification takes placebetween or in conjunction with the oxides on the immediately adjacent faces of the electrodes, previous proposals, to the best of my knowledge, having made use of oxide-to-metal contact.

The couples may be assembled in any suitable manner, and in the accompanying drawing have been shown, by way of example, two satisfactory assemblies.

Fig. 1 being a side view of a full wave rectifier 0f tubular form; and

.Fig ,2 a. side view of a full wave rectifier of cage form.

v In Fig. 1 the couples are enclosed in an insulating tube4 1 arranged within a metal tube that consists of two similar halves 2--2l joined together by screws passing through lugs 3 at their edges. The inner tube and the metal tube have in them registering openings and 5 respectively to 4enable connecting lugs 6 on lead spacers 7 to project to the outside ofthe outer tube where they receive terminals 8. 'I'he arrangement enables a full waverectier to be assembled in a very compact form, A. C. current being introduced at the outer of the terminals 8 and rectified current being available at the inner of the terminals 8 and alterminal 9 electrical connection with thetube and with .the

electrodes at each end. The tubes have additional holes 10 and 191v for'cooling purposes.

In Fig. 2 'the couples arealigned and secured 55 between two metal end plates 11-11 provided with clamping bolts such as 12 passing between the plates and through the corners thereof. Those parts of the bolts between the plates are surrounded by insulating sleeves such as 13 which centre vthe couples and leave' them free to'cool. The arrangement oi the couples and terminals is substantially they same asthat .of Fig. 1 the end plates and the bolts connecting the end= most couples and one o! the bolts having a' thumb nut 9.

Cooling lvaries may be used where necessary.

1. An alternating current rectifier comprising an Ealloy electrode containing aluminium, manganese and magnesium, .a paste electrode containing sulphur, selenium, manganese sulphide and antimony sulphide and a layer of al barium compound between said electrodes.

2. An alternatingy current rectifier comprising an electrode containing a film forming metal, an

. electrode containing metallic sulphides and a layer oi' a barium compound between said electrodes.

3. An alternating current rectifier comprising an electrode containing approximately 80% mage nesium, 1/2 to 20% aluminium and 20 to oi' manganese, a coating of a barium compound on a surface oi said electrode and a second electrode in contact with said coating comprising sulphur, selenium. magnesium sulphide and antimony sulphide in substantially the proportions 121:1:115 respectively by weight.

4. An alternating current rectifier comprising an alloy electrode containing aluminium, magnesium and manganese, an electrode comprising a metallic sulphide and a layer ci barium'oxide between said electrodes.

5.- An alternating current rectifier comprising an electrode containing a metal having lm=iorm ing properties, a second electrode comprising a metallic selenide, and a layer containing a barium compound between said electrodes.

6. A method oi making an alternating current rectier which comprises depositing a film of barium compound on the surface of an alloy of aluminium, magnesium vand manganese in 'an electrolytic bath and applying to said rllm under pressure a paste containing a metallic sulphide. I

'1. A method of making an alternating current rectier comprising forming a barium compound film on the surface ot an alloy lming electrode by. electrolytic action, applying to such lm under pressure a coating containing metallic sulphides and associating with said coating means Vfor making electrical contact therewith. 

